1. Field of the Invention
The present invention relates to curved honeycomb structural bodies.
2. Related Art Statement
Heretofore, honeycomb structural bodies have been produced by extrusion, or by corrugating a sheet and coiling it together with a flat sheet in a rolled fashion, or by forming a number of small projections in a metallic sheet in a scattered state through pressing and coiling it in a rolled fashion. These honeycomb structural bodies have a number of straight-line through holes.
When the conventional honeycomb structural bodies are used as catalyst carriers for the purification of exhaust gases from internal combustion engines in automobiles, there occur the following problems.
1 Since there is a limitation on a fitting site, it is impossible to install the catalyst carrier in a location having an optimum temperature condition as considered from the standpoint of high temperature durability and purification efficiency of the catalyst. PA1 2 Since the flow rate of the exhaust gas at the outer peripheral portion of the honeycomb structural body is smaller than that at the central portion thereof, a majority of the exhaust gas is purified in the central portion of the catalyst. Therefore, it cannot be said that the outer peripheral portion of the honeycomb structural body fully functions as the catalyst, which means poorer purification performance for the same volume of the catalyst. PA1 1 The center line possess at least two different radii R of curvature. The centers of curves bent at such at least two radii of curvature may be located on the same side as viewed relative to the plane passing the center line of the honeycomb structural body, or may be located on different sides. PA1 2 The honeycomb structural body includes a straightline portion in which said through holes are not bent is provided at least one location at an end portion of the honeycomb structural body or at a portion other than said end portion. PA1 3 The honeycomb structural body is made of a ceramic material. PA1 4 A catalyst is carried onto inner walls defining the through holes. PA1 5 The partition walls extend in orthogonal directions as viewed in section at right angles to said extending direction of said through holes, thereby defining two orthogonal axes as viewed in section, and said at least one line is parallel to one of said two orthogonal axes. PA1 6 The sectional shape of the honeycomb structural body as viewed in section orthogonal to said extending direction of the through holes is one selecting from the group consisting of a circular shape, an elliptical shape, an oval shape, a square shape, a rectangular shape and triangular shape.